BackgroundCardiovascular diseases (CVDs), the leading cause of death worldwide, are sensitive to temperature. In light of the reported climate change trends, it is important to understand the burden of CVDs attributable to temperature, both hot and cold. The association between CVDs and temperature is region-specific, with relatively few studies focusing on low-and middle-income countries. This study investigates this association in Puducherry, a coastal district in the Eastern part India for the first time.Methods We analyzed the association between apparent temperature (Tapp) and in-hospital CVD mortalities in Puducherry between 2010 and 2020 using a distributed lag non-linear model to capture the delayed and non-linear trends over a 21-day lag period and identify the optimal temperature range for Puducherry. The results are expressed as the fraction of CVD mortalities attributable to heat and cold, defined as temperatures above or below the optimal temperature. We also performed stratified analyses to explore the associations between Tapp and age-and-sex combined and different types of CVDs.Results We found that the optimal temperature range for Puducherry is between 33⁰C and 35⁰C with respect to CVDs. Both cold and hot non-optimal Tapp were associated with an increased risk of overall in-hospital CVD mortalities, resulting in a U-shaped association curve. Cumulatively, up to 20% of the CVD deaths could be attributable to non-optimal temperatures, with a slightly higher burden attributable to cold (11.2%) than heat (9.1%). We also found that males above 60 years of age were more vulnerable to colder temperature; females above 60 years were more vulnerable to heat while females below 60 years were affected by both heat and cold. Mortality with cerebrovascular accidents was associated more with heat compared to cold, while ischemic heart diseases did not seem to be affected by temperature.Conclusion Both heat and cold contribute to the burden of CVDs attributable to non-optimal temperatures in the tropical Puducherry. Our study also identified the age-and-sex and CVD type differences in temperature attributable CVD mortalities. Further studies from India could identify regional associations, inform our understanding of the health implications of climate change in India and enhance the development of regional and contextual climate-health action-plans.

Background and aimClimate change has far reaching consequences on all aspects of life, including health. Cardiovascular diseases (CVDs), the global leading cause of death, have also been found to be climate sensitive, mainly to temperature. However, the associations between CVDs and temperature are region-specific with relatively few studies focusing on low and middle-income countries. This study explores this association in Puducherry, a coastal district in the Eastern part India.Methods We analyzed the association between apparent temperature (Tapp) and in-hospital CVD mortalities in Puducherry between 2010 and 2020 using a binomial regression model. We used a distributed lag non-linear model to capture the delayed and non-linear trends and identify the optimal temperature range for Puducherry. The results are expressed as the fraction of CVD mortalities attributable to non-optimal temperatures. We also performed stratified analysis to explore the associations between Tapp and age and sex combined and different types of CVDs.Results We found that the optimal temperature range for Puducherry is between 33⁰C and 35⁰C with respect to CVDs. Temperatures both above and below the optimal temperature range were associated with an increased risk of overall in-hospital CVD mortalities, resulting in a U-shaped association curve. Up to 20% of the CVD deaths could be attributable to non-optimal temperatures, with a slightly higher burden attributable to cold (11.2%) than heat (9.1%). We also found that males above 60 years of age were more vulnerable to colder temperatures, while females above 60 years were more vulnerable to heat. Mortality with cerebrovascular accidents was associated more with heat compared to cold, while ischemic heart diseases did not seem to be affected by temperature.Conclusions We found the optimal temperature range for Puducherry to be higher than that previously reported for India as a whole, with a relatively high burden attributable to ‘cold’ temperatures, despite being an inherently hot region. Our study also identified the age and gender differences in temperature attributable CVD mortalities, which can be socio-cultural. Further studies from India could identify the regional associations and enhance the development of region and context specific climate-health action plans.

ObjectiveTo assess the cost-effectiveness of using cheap-but-noisy outcome measures, such as a short and simple questionnaire.BackgroundTo detect associations reliably, studies must avoid bias and random error. To reduce random error, we can increase the size of the study and increase the accuracy of the outcome measurement process. However, with fixed resources there is a trade-off between the number of participants a study can enrol and the amount of information that can be collected on each participant during data collection.MethodTo consider the effect on measurement error of using outcome scales with varying numbers of categories we define and calculate the Variance from Categorisation that would be expected from using a category midpoint; define the analytic conditions under-which such a measure is cost-effective; use meta-regression to estimate the impact of participant burden, defined as questionnaire length, on response rates; and develop an interactive web-app to allow researchers to explore the cost-effectiveness of using such a measure under plausible assumptions.ResultsCompared with no measurement, only having a few categories greatly reduced the Variance from Categorization. For example, scales with five categories reduce the variance by 96% for a uniform distribution. We additionally show that a simple measure will be more cost effective than a gold-standard measure if the relative increase in variance due to using it is less than the relative increase in cost from the gold standard, assuming it does not introduce bias in the measurement. We found an inverse power law relationship between participant burden and response rates such that a doubling the burden on participants reduces the response rate by around one third. Finally, we created an interactive web-app (https://benjiwoolf.shinyapps.io/cheapbutnoisymeasures/) to allow exploration of when using a cheap-but-noisy measure will be more cost-effective using realistic parameter.ConclusionCheap-but-noisy questionnaires containing just a few questions can be a cost effect way of maximising power. However, their use requires a judgment on the trade-off between the potential increase in risk information bias and the reduction in the potential of selection bias due to the expected higher response rates.Key Messages-A cheap-but-noisy outcome measure, like a short form questionnaire, is a more cost-effective method of maximising power than an error free gold standard when the percentage increase in noise from using the cheap-but-noisy measure is less than the relative difference in the cost of administering the two alternatives.-We have created an R-shiny app to facilitate the exploration of when this condition is met at https://benjiwoolf.shinyapps.io/cheapbutnoisymeasures/-Cheap-but-noisy outcome measures are more likely to introduce information bias than a gold standard, but may reduce selection bias because they reduce loss-to-follow-up. Researchers therefore need to form a judgement about the relative increase or decrease in bias before using a cheap-but-noisy measure.-We would encourage the development and validation of short form questionnaires to enable the use of high quality cheap-but-noisy outcome measures in randomised controlled trials.

Background Climate change has far-reaching consequences on human health globally. Cardiovascular diseases (CVDs), the global leading cause of death, are climate sensitive, mainly to temperature. The temperature-CVD association is region-specific, with several studies from Europe but relatively few from low-and-middle-income countries (LMICs). Methods We used a binomial regression model to analyze the association between apparent temperature and in-hospital CVD mortality in Puducherry city. A distributed lag non-linear model was used to capture the delayed and non-linear trends over a 21 day lag period to estimate the burden of in-hospital CVD mortalities attributable to non-optimal temperature between 2010 and 2020. Results Tapp in Puducherry ranges from 23°C to 40°C. We found that the optimal temperature range for Puducherry is between 33°C and 35°C with respect to CVDs. Temperatures both above and below the optimal temperature range were associated with an increased risk of overall in-hospital CVD mortalities, resulting in a U-shaped association curve. Up to 20% of the CVD deaths could be attributable to non-optimal temperatures, with a slightly higher burden attributable to cold (11.2%) than heat (9.12%). We also found that males above 60 years of age were more vulnerable to colder temperatures while females above 60 years were more vulnerable to the heat. Mortality with cerebrovascular accidents was associated more with heat compared to cold, and ischemic heart diseases did not seem to be affected by temperature. Conclusions Both cold and heat is associated with CVD mortality in Puducherry. The comparison of the results of this exploratory Indian study with those from European contexts show that the associations differ based on several factors. There are also age, gender and CVD type differences in Tapp attributable CVD mortalities. More region specific studies on Tapp- CVD mortality are needed from LMICs to better understand this association and build capacity. Key messages • The regional burden of cold attributable CVD deaths needs to be considered along with heat. Age and gender specific differences in the association need to be further studied globally. • The development regional and contextual climate-health action plans, as seen in some European countries, could be enhanced by such studies and reduce the burden of temperature attributable CVD deaths.

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